Percutaneous posterior spinal fusion implant construction and method

ABSTRACT

A system includes tubular members removably positionable over a passageway device connected to a connecting element attached to a vertebra. The tubular members may each include a sidewall having an opening positionable adjacent a proximal end of the passageway device when the tubular member is positioned over the passageway device. The tubular members include channels therein to receive respective blades of the passageway devices. One of the tubular members may be a counter torque tube, and another two of the tubular members may be a hinge shaft and a ball shaft, respectively, of a compression and distraction system. The blades of each passageway device may be integrally formed with a cage of the connecting element to form a monolithic blade-screw. The blades of the monolithic blade-screw may be constructed by affixing distal ends of non-threaded blade extensions to proximal ends of threaded reduction portions integrally connected to the cage.

BACKGROUND OF THE INVENTION

The present invention relates to the percutaneous insertion of spinalfusion implants into the body of a patient and the affixation of thoseimplants to the spine. In particular, the invention includespercutaneous posterior spinal fusion systems, devices used inconjunction with such systems, and associated methods.

Pedicle screw fixation constructs have been in use for decades in orderto fuse adjacent vertebral segments to improve spinal stability orcorrect certain spinal deformities. Older approaches for inserting thesefixation constructs involved open procedures, in which relatively largeskin incisions were created to expose a substantial portion of thepatient's spinal column, in order to allow for insertion of the pediclescrews and manipulation of spinal rods through openings adjacent to theheads of the screws.

Over time, less invasive approaches have been developed. Typically, insuch approaches, pedicle screws are inserted into the pedicles of thesame or adjacent vertebrae of a patient's spine through individualpercutaneous incisions corresponding to the pedicle screws. Fixation orfusion rods are then inserted into the body through one of thoseincisions, or through an additional incision adjacent to the mostcephalad or caudal pedicle screw, and the rod is rigidly connected tothe pedicle screws such that the rod extends along the longitudinal axisof the spine (i.e., along the cephalad/caudal direction) in order to fixthe relative positions of the adjacent vertebrae to which the rod isconnected. In some such minimally invasive procedures, a device (e.g., acannula, tower, or portal) is connected to each of the pedicle screwsand extends through the respective percutaneous incision. Moreover, itis known to utilize separate elongate blades connected with the screws.Such devices provide a percutaneous passageway through the tissue fromeach incision to the respective pedicle screw, in order to aid in theinsertion of a spinal rod. Examples of such passageway devices aredescribed in commonly-assigned U.S. Pat. No. 7,955,355 (“the '355Patent”) and U.S. Pat. No. 8,002,798 (“the '798 Patent”), the entiretiesof which are hereby incorporated by reference herein as if fully setforth herein.

Although considerable effort has been devoted in the art to optimizationof such minimally invasive systems, still further improvement would bedesirable.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention provides a system for manipulatingportions of a spinal fusion system. The system according to this aspectof the invention desirably includes a connecting element, a passagewaydevice, and a tubular member. The connecting element is preferablyattachable to a vertebra of the spine, and a distal end of thepassageway device is preferably connected to the connecting element. Thetubular member preferably has an opening through its sidewall betweenits proximal and distal ends, and the tubular member is preferablyremovably positionable over the passageway device in an insertedposition. In that position, an open interior portion of the tubularmember preferably receives the passageway device within it.

According to another aspect of the invention, the tubular member may bestructured such that, when it is positioned in the inserted position,its distal end is positioned proximate the connecting element and afeature of the passageway device is positioned adjacent to the opening.According to a further aspect of the invention, the feature may be theproximal end of the passageway device. According to yet another aspectof the invention, the sidewall of the tubular member may include avisible marking proximate the opening. In accordance with a furtheraspect of the invention, the visible marking may be indicative of alength of the passageway device. According to another aspect of theinvention, the tubular member may include a second opening through itssidewall between the proximal and distal ends.

According to other aspects of the invention, the tubular member may be acounter torque tube having a handle projecting laterally therefrom.According to a further aspect of the invention, the distal end of thetubular member may be structured to engage the connecting element in theinserted position so as to prevent relative rotation between theconnecting element and the tubular member.

According to another aspect of the invention, the system may furtherinclude a second connecting element, a second passageway device, and asecond tubular member. The second connecting element is preferablyattachable to a second vertebra of the spine, and a distal end of thesecond passageway device is preferably connected to the secondconnecting element. The second tubular member is desirably removablypositionable over the second passageway device in a second insertedposition. In that position, a second open interior portion of thetubular member preferably receives the second passageway device withinit. The second tubular member may be movably connectable to the tubularmember to allow for compression and distraction of the first and secondvertebrae.

According to yet another aspect of the invention, the passageway devicemay include a first blade having a distal end connected to theconnecting element, and the open interior portion of the tubular membermay receive the first blade in the inserted position. In accordance witha further aspect of the invention, the open interior portion of thetubular member may include a first channel that receives the first bladewhen the tubular member is positioned in the inserted position.According to another aspect of the invention, the passageway device mayinclude a second blade having a distal end connected to the connectingelement, and the open interior portion of the tubular member may receivethe second blade in the inserted position. In accordance with a furtheraspect of the invention, the open interior portion of the tubular membermay include first and second channels that receive the respective firstand second blades when the tubular member is positioned in the insertedposition.

Another aspect of the present invention that provides a system formanipulating portions of a spinal fusion system desirably includes aconnecting element attachable to a vertebra of the spine; a tubularmember; and first and second blades, each of which has a distal endconnected to the connecting element. The tubular member preferably hasfirst and second channels formed therein that receive the respectivefirst and second blades when the tubular member is positioned in aninserted position in which its distal end is proximate the connectingelement.

According to yet another aspect of the invention, the system desirablyfurther includes a second connecting element attachable to a secondvertebra of the spine; a second tubular member; and third and fourthblades, each of which has a distal end connected to the secondconnecting element. The second tubular member preferably has third andfourth channels formed therein that receive the respective third andfourth blades when the second tubular member is positioned in a secondinserted position in which its distal end is proximate the secondconnecting element.

According to other aspects of the invention, the tubular member may havean opening through its sidewall between proximal and distal ends of thetubular member. In accordance with a further aspect of the invention,the sidewall of the tubular member may include a visible markingproximate the opening.

Yet another aspect of the present invention that provides a system formanipulating portions of a spinal fusion system desirably includes afirst shaft, a second shaft, and a manipulation device. The first andsecond shafts preferably have a respective first and second connector,and the distal ends of the first and second shafts are preferablyconnectable to respective first and second connecting elements affixedto respective first and second vertebrae of the spine. Desirably, thefirst connector is rotatable about the longitudinal axis of the firstshaft. The manipulation device may be connectable to the first andsecond connectors and adapted to move the first and second shafts withrespect to one another to induce relative movement between the first andsecond vertebrae.

According to one aspect of the invention, the second connector may berotatable about the longitudinal axis of the second shaft. According toanother aspect of the invention, the manipulation device may be acompressor adapted to move the first and second shafts towards oneanother. According to yet another aspect of the invention, themanipulation device may be a distractor adapted to move the first andsecond shafts away from one another. According to a further aspect ofthe invention, the first connector may be positioned in a middle portionof the first shaft between the proximal and distal ends of the firstshaft. In accordance with another aspect of the invention, the proximalends of the first and second shafts may be movably connectable to oneanother. In accordance with a further aspect of the invention, theproximal ends of the first and second shafts may be pivotablyconnectable together at a pivot point.

According to another aspect of the invention, the first shaft may havean open interior portion adapted to receive a passageway deviceextending proximally from the first connecting element. According to afurther aspect of the invention, the passageway device may include afirst blade having a distal end connected to the connecting element, andthe open interior portion of the first shaft may include a first channeladapted to receive the first blade when the passageway device isreceived within the open interior portion. In accordance with anotheraspect of the invention, the first and second connecting elements mayeach include a respective anchoring element and coupling element, theanchoring element being affixable to a pedicle of a respective vertebra,and the coupling element being adapted to receive a spinal fusionelement. In accordance with this aspect of the invention, the distalends of the first and second shafts may be connectable to the respectivefirst and second coupling elements.

Another aspect of the present invention that provides a system formanipulating portions of a spinal fusion system desirably includes afirst shaft, a second shaft, and a manipulation device. The first andsecond shafts preferably have a respective first and second connector,and the distal ends of the first and second shafts are preferablyconnectable to respective first and second connecting elements affixedto respective first and second vertebrae of the spine. Desirably, thefirst and second connecting elements each have a passageway deviceextending proximally therefrom, and the first and second shaftsdesirably each have an open interior portion adapted to receive therespective passageway device therein when the distal end of therespective shaft is connected to the respective connecting element. Themanipulation device may be connectable to the first and secondconnectors and adapted to move the first and second shafts with respectto one another to induce relative movement between the first and secondvertebrae.

In accordance with other aspects of the invention, a first passagewaydevice extending proximally from the first connecting element mayinclude first and second blades each having a distal end connected tothe first connecting element. In accordance with this aspect of theinvention, the open interior portion of the first shaft may include afirst and second channel adapted to receive the respective first andsecond blades when the first passageway device is received within theopen interior portion of the first shaft. According to a further aspectof the invention, a second passageway device extending proximally fromthe second connecting element may include third and fourth blades eachhaving a distal end connected to the second connecting element. Inaccordance with this aspect of the invention, the open interior portionof the second shaft may include a third and fourth channel adapted toreceive the respective third and fourth blades when the secondpassageway device is received within the open interior portion of thesecond shaft.

Another aspect of the present invention provides a method ofmanipulating portions of a spinal fusion system. The method according tothis aspect of the invention desirably includes: connecting a distal endof a first shaft to a first connecting element affixed to a firstvertebra of a spine, the first shaft including a first connector;connecting a distal end of a second shaft to a second connecting elementaffixed to a second vertebra of the spine, the second shaft including asecond connector; and manipulating a manipulation device connected tothe first and second connectors so as to move the first and secondshafts with respect to one another to induce relative movement betweenthe first and second vertebrae. In accordance with this aspect of theinvention, the first connector is preferably rotatable about thelongitudinal axis of the first shaft.

In accordance with a further aspect of the invention, the firstconnector may rotate about the longitudinal axis of the first shaftduring the step of manipulating the manipulation device. In accordancewith another aspect of the invention, the second connector may berotatable about a longitudinal axis of the second shaft. According toyet another aspect of the invention, the step of manipulating themanipulation device may include pivoting first and second arms of themanipulation device, each arm being connected to the respective firstand second connector.

In accordance with another aspect of the invention, where the firstvertebra may be located on a first side of the second vertebra, themethod preferably further includes: disconnecting the distal end of thefirst shaft from the first connecting element; repositioning the firstshaft on a second side of the second vertebra opposite the first side;and connecting the distal end of the first shaft to a connecting elementaffixed to a third vertebra located on the second side of the secondvertebra. In accordance with a further aspect of the invention, themethod may further include rotating the second connector of the secondshaft towards the first shaft. In accordance with yet a further aspectof the invention, the method may further include connecting themanipulation device to the first and second connectors. According to afurther aspect of the invention, the method may further includedisconnecting a proximal end of the first shaft from a proximal end ofthe second shaft before the step of repositioning the first shaft on thesecond side of the second vertebra. According to yet a further aspect ofthe invention, the method may further include reconnecting the proximalend of the first shaft with the proximal end of the second shaft afterthe step of repositioning the first shaft on the second side of thesecond vertebra. In accordance with yet a further aspect of theinvention, the step of disconnecting the proximal end of the first shaftfrom the proximal end of the second shaft may comprise uncoupling areceiver element at the proximal end of the second shaft from anengagement end at the proximal end of the first shaft, and the step ofreconnecting the proximal end of the first shaft with the proximal endof the second shaft may include reorienting the receiver element andcoupling the receiver element to the engagement end. According to yet afurther aspect of the invention, the step of reorienting the receiverelement may include rotating the receiver element from the first side ofthe second vertebra to the second side of the second vertebra.

According to another aspect of the invention, the first and secondconnectors may each be positioned in a middle portion of the respectivefirst and second shafts between the proximal and distal ends of therespective shafts. According to yet another aspect of the invention, themethod may further include receiving a first passageway device withinthe first shaft and receiving a second passageway device within thesecond shaft, which first and second passageway devices extendproximally from the respective first and second connecting elements. Inaccordance with yet another aspect of the invention, the method mayfurther include connecting a proximal end of the first shaft to aproximal end of the second shaft. In accordance with a further aspect ofthe invention, the proximal ends of the first and second shafts may beconnected such that, during the step of manipulating the manipulationdevice connected to the first and second connectors, the first andsecond shafts pivot about a pivot point proximate the proximal ends ofthe first and second shafts.

Another aspect of the present invention provides a method ofconstructing a monolithic blade-screw. The method according to thisaspect of the invention desirably includes providing a connectingelement including a screw coupled to a cage. The cage is preferablyadapted to receive a spinal fusion rod in it, and the cage preferablyhas a reduction portion connected to it at a frangible portion. Themethod according to this aspect of the invention desirably also includesaffixing a distal end of a blade extension to a proximal end of thereduction portion.

According to another aspect of the invention, the method may furtherinclude integrally forming the cage and the reduction portion from asingle piece of material. According to a further aspect of theinvention, the cage and the reduction portion may include threadstherealong, and the blade extension may not be threaded. According toyet a further aspect of the invention, the threads may have a generallyhorizontal flank facing towards the screw. According to yet anotheraspect of the invention, the step of affixing the distal end of theblade extension to the proximal end of the reduction portion may includewelding the distal end of the blade extension to the proximal end of thereduction portion. According to another aspect of the invention, thescrew may be polyaxially coupled to the cage. In accordance with anotheraspect of the invention, the method may further include modifying theshape of a component forming the blade extension. According to furtheraspects of the invention, the step of modifying the shape of thecomponent may occur either before or after the step of affixing thedistal end of the blade extension to the proximal end of the reductionportion. According to yet another aspect of the invention, the step ofmodifying the shape of the component may be performed by wire-cutelectrical discharge machining. In accordance with yet another aspect ofthe invention, the method may further include coupling the screw to thecage before the step of providing the connecting element.

Another aspect of the present invention provides a monolithicblade-screw. The blade-screw according to this aspect of the inventiondesirably includes a connecting element and a blade extension. Theconnecting element preferably includes a screw coupled to a cage. Thecage may be adapted to receive a spinal fusion rod in it, and the cagemay have a reduction portion connected to it at a frangible portion.Desirably, a distal end of the blade extension may be affixed to aproximal end of the reduction portion.

According to another aspect of the invention, the cage and the reductionportion may be integrally formed from a single piece of material.According to a further aspect of the invention, the cage and thereduction portion may include threads therealong, and the bladeextension may not be threaded. According to yet a further aspect of theinvention, the threads may have a generally horizontal flank facingtowards the screw. According to yet another aspect of the invention, thedistal end of the blade extension may be affixed to the proximal end ofthe reduction portion by a weld. In accordance with another aspect ofthe invention, the screw may be polyaxially coupled to the cage. Inaccordance with yet another aspect of the invention, a profile of theblade extension may vary between its proximal and distal ends.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a system of blade-screws connected to aspine, in accordance with an embodiment of the present invention.

FIG. 2A is a perspective view of a blade-screw of FIG. 1.

FIG. 2B is a sectional view of the blade-screw of FIG. 2A.

FIG. 3A is a perspective view of a system of blade-screws connected to aspine and being used for contouring a rod, in accordance with anembodiment of the present invention.

FIG. 3B is a plan view of a template rod, in accordance with anembodiment of the present invention.

FIG. 4A is a partial, perspective view of a rod inserter and rod, inaccordance with an embodiment of the present invention.

FIGS. 4B-C are perspective views of the rod inserter of FIG. 4Ainserting the rod into a body through the system of blade-screws of FIG.1.

FIG. 5A is a perspective view of a set screw, in accordance with anembodiment of the present invention.

FIG. 5B is a partial, perspective view of the set screw of FIG. 5Aengaged with a set screw driver, in accordance with an embodiment of thepresent invention.

FIG. 6 is a perspective view of the system of blade-screws of FIG. 1,the rod inserter and rod of FIGS. 4A-C, the set screw driver of FIG. 5B,and a counter torque tube, all being used together, in accordance withan embodiment of the present invention.

FIG. 7A is a perspective view of the counter torque tube of FIG. 6.

FIG. 7B is a partial, sectional view of the counter torque tube of FIG.7A.

FIGS. 8A-B are partial, elevational views of the counter torque tube ofFIG. 7A.

FIG. 9A is a perspective view of the system of blade-screws of FIG. 1being used with components of a compression and distraction system inone configuration, in accordance with an embodiment of the presentinvention.

FIG. 9B is a perspective view of the system of blade-screws of FIG. 1being used with the components of the compression and distraction systemof FIG. 9A in another configuration, in accordance with an embodiment ofthe present invention.

FIGS. 10A-B are elevational views of a hinge shaft of the compressionand distraction system of FIGS. 9A-B.

FIGS. 11A-B are elevational views of a ball shaft of the compression anddistraction system of FIGS. 9A-B.

FIG. 12A is a plan view of a distractor for use with a compression anddistraction system in accordance with an embodiment of the presentinvention.

FIG. 12B is a perspective view of the distractor of FIG. 12A being usedwith the components of the compression and distraction system in theconfiguration of FIG. 9B.

FIG. 13A is a plan view of a compressor for use with a compression anddistraction system in accordance with an embodiment of the presentinvention.

FIG. 13B is a perspective view of the compressor of FIG. 13A being usedwith the components of the compression and distraction system in theconfiguration of FIG. 9B.

FIG. 14A is an elevational view of a blade remover, in accordance withan embodiment of the present invention.

FIGS. 14B-C are perspective views of the blade remover of FIG. 14A beingused with the system of blade-screws of FIG. 1.

FIG. 14D is an elevational view of the blade remover of FIG. 14Aejecting a blade of a blade-screw, in accordance with an embodiment ofthe present invention.

DETAILED DESCRIPTION

Where reference is made herein to directional terms such as “proximal,”“proximal most,” “distal,” and “distal most,” it is to be understoodthat “proximal” and “proximal most” refer to locations closer to a useror operator of the device or method being described and that “distal”and “distal most” refer to locations further from a user or operator ofthe device or method being described.

FIG. 1 illustrates a system of connecting elements 30, passagewaydevices 31, and a spinal fusion element or rod 44 connected to a spine10. The spine 10 has a cephalad direction 12, a caudal direction 14, ananterior direction 16, a posterior direction 18, and a medial/lateralaxis 20, all of which are oriented as shown by the arrows bearing thesame reference numerals. In this application, “left” and “right” areused with reference to a posterior view, i.e., a view from behind thespine 10. “Medial” refers to a position or orientation toward a sagittalplane (i.e., plane of symmetry that separates left and right sides fromeach other) of the spine 10, and “lateral” refers to a position ororientation relatively further from the sagittal plane.

As shown in FIG. 1, the spine 10 includes a first vertebra 22, a secondvertebra 24, and a third vertebra 26. The systems and methods herein maybe applicable to any vertebra or vertebrae of the spine 10 and/or thesacrum 11. As such, the term “vertebrae” may be broadly interpreted toinclude all vertebrae, as well as the sacrum. As shown in the figure,the connecting elements 30 and associated passageway devices 31 areconnected to respective pedicles 36, 38, 40 on the right side of therespective first, second, and third vertebrae 22, 24, 26. Although thesystem illustrated in FIG. 1 spans three vertebrae, other embodiments ofsystems in accordance with the present invention may span fewer or morevertebrae. For example, additional connecting elements 30 and passagewaydevices 31 may be connected to additional vertebrae along the spine 10.

The connecting elements 30 each include an anchoring element or screw 32(see FIGS. 2A-B) implanted in the respective pedicles 36, 38, 40 and acoupling element or cage 42 for receiving the spinal fusion rod 44therein. The cages 42 may be coupled to the respective screws 32 invarious ways known in the art. For example, as shown in FIG. 2B, thecages 42 and the screws 32 may be polyaxially coupled. In otherembodiments (not shown), the coupling between the cages 42 and thescrews 32 may be a monoaxial coupling or a uniplanar coupling, or thecages 42 may be rigidly fixed to (e.g., integrally formed with) thescrews 32. Each connecting element 30 may also include a set screw 45for securing the rod 44 within the cage 42. The connecting elements 30may have the same or similar structure as the connecting elementsdescribed in the '798 Patent. Alternatively, the connecting elements 30may have the same or similar structure as the pedicle screws describedin U.S. Pat. No. 7,988,713 (“the '713 Patent”) or the pedicle screws,pedicle hooks, or lamina hooks described in U.S. Pat. No. 6,074,391(“the '391 Patent”). The entire disclosures of the '713 Patent and the'391 Patent are hereby incorporated by reference herein as if fully setforth herein. Although the anchoring elements are illustrated herein asscrews 32, it is to be understood that other types of anchoring elementscapable of being secured to vertebral bone may be used, such as theabove-referenced hooks described in the '391 Patent. Moreover, althoughthe spinal fusion element 44 is illustrated herein as a rod 44, it is tobe understood that other types of elements capable of securing togetheradjacent vertebrae may be used, such as plates, wires, rods, orarticulating versions thereof.

The connecting elements 30 may be percutaneously inserted in the body inthe same manner as described in the '798 Patent. That is, each of theconnecting elements 30 may be inserted along a respective guide wirethrough a separate incision 46, 48, 50 in the skin 51. Sequentialdilators may be used to enlarge the passageway between the incisions 46,48, 50 and the respective pedicles 36, 38, 40. The screws 32 of theconnecting elements 30 may be implanted in previously tapped bores inthe associated pedicles, or the screws 32 may self-tap into thepedicles. The advancement of each screw 32 into a pedicle may be drivenby a driver (not shown) having a distal end engaged with a driverinterface 34 on the head 35 of the screw 32 (see FIG. 2B), such that ashaft of the driver extends proximally within the passageway device 31.The driver interface 34 of the head 35 may take the form of thatdisclosed in U.S. Pat. No. 8,231,635 (“the '635 Patent”), the entiredisclosure of which is hereby incorporated by reference herein as iffully set forth herein, and the driver may take the form of any one ofthe screwdrivers disclosed in that patent. The driver may be a poweredor a manually operated driver. Additionally, before the connectingelements 30 are inserted into the body, spinal navigation softwareand/or robotics may be used to help locate the appropriate pedicles 36,38, 40 and to implant or help guide the implantation of the connectingelements 30 into the pedicles.

The passageway devices 31 are connected to the connecting elements 30such that the passageway devices 31 extend proximally from theconnecting elements 30 though the respective incisions 46, 48, 50. Inparticular, as shown in FIGS. 2A-B, the distal ends 52 of the passagewaydevices 31 are connected to the proximal ends 54 of the cages 42. Thepassageway devices 31 each provide a passageway 55 extending along anaxis 57 from the incision 46, 48, 50 to the respective connectingelement 30 to aid the percutaneous insertion of the rod 44. The axis 57(and the associated passageway device 31) may be straight, asillustrated in the figures herein, or the passageway device 31 maydefine an angled or curved longitudinal axis, as disclosed in certainembodiments of U.S. patent application Ser. No. 14/034,021 (“the '021Application”), filed on Sep. 23, 2013 and entitled “Lumbar-Sacral ScrewInsertion and Manipulation,” the entire disclosure of which is herebyincorporated by reference herein as if fully set forth herein. Eachpassageway device 31 may take the form of two blades 56 attached toopposing arms 58 of the associated cage 42. The blades 56 may beseparately formed from and detachably connectible to the cages 42, asdescribed in the '798 Patent. Alternatively, the blades 56 may be formedas a single piece with the associated cages 42, as also described in the'798 Patent. For example, FIGS. 1-2B illustrate an embodiment in whichthe blades 56 are integrally connected to the associated cages 42 toform monolithic blade-screws 60. In such an embodiment, the blades 56may be connected to the cages by frangible portions 62. Each frangibleportion 62 may include a reduced thickness portion, which may be definedby grooves formed in either or both of the interior and exteriorsurfaces of the blade-screws 60 at the junction between the blades 56and the respective arms 58 of the cages 42. In the embodimentillustrated in FIG. 2B, the frangible portions 62 are defined by agroove 64 along the exterior of the blade-screw 60 and a groove 66 alongthe interior of the blade-screw 60 that is aligned with the exteriorgroove 64. The frangible portions 62 provide a location for the blades56 to be broken away from the cages 42 when desired.

The interior of each cage 42 may include threads 68 along the arms 58,and the passageway device 31 may include reduction threads 70 at leastalong the distal end 52 thereof. In other embodiments (not shown), thereduction threads 70 of the passageway device 31 may not be presentwhile the threads 68 of the cage 42 are present. The set screw 45 (seeFIG. 5A) is an externally threaded component structured to engage thereduction threads 70 of the passageway device 31 and the threads 68 ofthe cage 42. Both threads 68 and 70 are aligned such that the set screw45 can be rotatably advanced distally along the reduction threads 70 ofthe passageway device 31, after which continued rotation of the setscrew 45 will cause the set screw 45 to engage and advance along thethreads 68 of the cage 42.

The threads 68 and/or the reduction threads 70 may have a tooth shape asdisclosed in the '391 Patent. That is, as disclosed in the '391 Patent,and as illustrated in FIG. 2B herein, the flank of each thread facing inthe distal direction (i.e., towards the screw 32) may be steep and,preferably, is generally horizontal, and the flank of each thread facingin the proximal direction (i.e., away from the screw 32) may be angledat about 30° with respect to the horizontal. The threads 106 of the setscrew 45 are preferably complementary to the threads 68 and/or thereduction threads 70 (i.e., the steep flank of each thread 106 of theset screw 45 may be aligned oppositely to the steep flanks of thethreads 68, 70).

As discussed above, the blades 56 of the passageway devices 31 areintegrally connected to the cages 42 in the monolithic blade-screws 60.Such blade-screws 60 may be constructed by fabricating each cage 42 withits respective passageway device 31 as one piece. For example, a cage 42with two blades 56 extending therefrom may be machined out of a singlepiece of material. In another example, the cage 42 with both blades 56may be cast or molded as a unitary component. In other embodiments,however, subcomponents of the cage 42 and passageway device 31 may beformed separately and then integrally connected together, such as bywelding. For example, the blades 56 and the cages 42 may be separatelyformed (e.g., by machining, casting, or molding), and the distal ends 52of two blades 56 defining a passageway device 31 may be connected (e.g.,by welding) to the proximal ends 54 of the arms 58 of a cage 42. In thecase of welding, the welded regions may form the frangible portions 62.In yet another embodiment, each cage 42 may be integrally formed (e.g.,by machining, casting, or molding) with two reduction portions 61extending proximally from the proximal ends 54 of each of the arms 58 ofthe cage 42. The reduction portions 61 desirably include the reductionthreads 70 of what will become the blades 56. Two blade extensions 63may be separately formed, and the distal ends 65 of those extensions 63may be integrally connected (e.g., welded) to the proximal ends 67 ofthe reduction portions 61 at connection 69. As shown in FIGS. 2A-B, eachblade extension 63 may have a particular shape or profile that changesalong its length. The final shape of the blade extensions 63 may becreated when the separately formed blade extensions 63 are initiallyfabricated (e.g., machined, casted, or molded). Alternatively, the bladeextensions 63 may initially be formed into larger pieces, which are thenfurther refined to arrive at their final shape. For example, wire-cutelectrical discharge machining (“EDM”) may be used to modify the shapeof the initially formed larger pieces in order to arrive at the finalshape of the blade extensions 63. Such modifications (e.g., usingwire-cut EDM) may be performed either before or after the bladeextensions 63 are integrally connected to the reduction portions 61.

In some embodiments, the height of the cages 42 (i.e., the length alonglongitudinal axis 57) may be about 1.5 cm. The blades 56 may rangebetween about 5 cm long and about 15 cm long. The reduction portions 61may represent any portion of the length of the blades 56, e.g., about 1cm to about 4 cm, but may preferably be about 2 cm in length. Systems inaccordance with embodiments of the invention may include blade-screws 60having blades 56 of different lengths, for example, because thedistances to be traversed between the skin along a patient's back andthe underlying pedicles may be different for different sized patients.For example, such systems may include blades 56 of two different lengths(i.e., long blades and short blades). In an exemplary embodiment, thelong blades may be about 11 cm long, and the short blades may be about 7cm long. Although the reduction portions 61 may represent any portion ofthat length, the reduction portions 61 may have the same length in boththe long and short blades. For example, in an embodiment in which thereduction portions are about 2 cm, as discussed above, the bladeextensions 64 of the short blades may be about 5 cm long and the bladeextensions 64 of the long blades may be about 9 cm long.

Referring to FIG. 1, a coupling 72 may be connected to the blades 56 ofeach passageway device 31 along the length of the passageway device 31.The couplings 72 may take the form of those disclosed in U.S.Provisional Patent Application No. 61/783,098 (“the '098 Application”),filed on Mar. 14, 2013 and entitled “Systems and Methods forPercutaneous Spinal Fusion,” the entire disclosure of which is herebyincorporated by reference herein as if fully set forth herein. In otherembodiments, the coupling may take the form of the abutment membersdisclosed in the '798 Patent. In addition, the couplings 72 may beconnected to the blades 56 in the same manner as disclosed in the '098Application or the '798 Patent. For example, as disclosed in the '098Application, the couplings 72 may include flexible tabs 74 having a bossor protuberance (not shown) extending inwardly therefrom for engagingholes 76 along the length of the blades 56. The couplings 72 may alsoinclude recesses 78 to provide an extracorporeal template for contouringor selecting the rod 44 to be implanted, as disclosed in the '098Application. Such contouring or selection may also be done in the mannerdisclosed in commonly owned U.S. Pat. No. 8,177,817 (“the '817 Patent”)or U.S. Patent Application Publication No. 2007/0233079 (“the '079Publication”), the entireties of which are hereby incorporated byreference herein as if fully set forth herein.

Referring to FIG. 3A, a rod 44 is shown seated in the recesses 78 of thecouplings 72 attached to two adjacent passageway devices 31. The rod 44may be contoured (e.g., with a French bender or with an automated orrobotic rod bending system in the operating room), selected from a kitof pre-shaped rods, or custom fabricated (e.g., by a CNC procedure) suchthat the rod 44 provides an optimal fit within the recesses 78, andthus, in turn, within the cages 42 of the connecting elements 30.Alternatively, a template rod 80, as shown in FIG. 3B, may be seated inthe recesses 78 of the couplings 72. The template rod 80 may be similarin shape to rod 44 but may be easier to bend, particularly by hand, andmay also include measurement markings 82 along its length. The templaterod 80 may be bent and seated within the recesses 78, which steps may berepeated as necessary until the template rod 80 approximates the desiredshape of the rod 44 to be implanted in the cages 42. The template rod 80may then be used as a reference in contouring, selecting, or fabricatingthe rod 44 to be implanted.

Once a rod 44 having the desired contour has been selected, it may beconnected to a rod inserter 84, as shown in FIG. 4A. The rod inserter 84is an elongate tool having a handle (see FIGS. 4B-C) at its proximal end88 and a connection structure 90 at its distal end 92 for detachablyconnecting to the rod 44. The proximal end 88 of the rod inserter 84 mayalso include an actuator 94 configured to operate the connectionstructure 90 so as to selectively secure and release the rod 44 to theconnection structure 90. The rod 44 may be designed with a particularshape at one end for secure gripping by the connection structure 90 ofthe rod inserter 84. For example, the outer surface of the rod 44 at oneend may have one or more flat sides (e.g., the rod may have a hexagonalcross-sectional profile at that end), and the interaction between theflat sides and the connection structure 90 may prevent rotation of therod 44 about its longitudinal axis. The connection structure 90 may alsobe structured to securely grip the rod 44 while the rod 44 extends awayat an angle to the rod inserter 84. For example, the rod 44 may extendat an approximately 90° angle to the rod inserter 84, as shown in FIG.4A. In another embodiment, the rod 44 may extend at a 110° angle. In yetanother embodiment, the connection structure 90 may be adjustable suchthat the angle of the rod 44 with respect to the rod inserter 84 can bevaried.

Once the rod 44 is attached to the rod inserter 84, the handle 86 of therod inserter 84 may be grasped and used to manipulate the rod 44 intothe body, as shown in FIGS. 4B-C, until the rod 44 extends between thecages 42 of the implanted connecting elements 30. For example, as shownin FIG. 4B, the far end 96 of the rod 44 opposite to the end 98connected to the rod inserter 84 may be inserted through an incision 46at one end of the system of blade-screws 60. That far end 96 of the rod44 may then be passed subcutaneously across between the blades 56 of thepassageway devices 31 until it is seated in the cage 42 of theconnecting element 30 at the other end of the system of blade-screws 60.Then, as shown in FIG. 4C, the rod inserter 84 may be used to manipulatethe end 98 of the rod 44 connected to the inserter 84 downwards untilthat end 98 is seated in the cage 42 of the connecting element 30beneath the incision 46.

Once the rod 44 is seated in the cages 42 of the connecting elements 30attached to the vertebrae 22, 24, 26, a set screw 45, as shown in FIG.5A, may be advanced into each of the cages 42. The set screw 45 includesa driving interface 100 engageable with the distal end 102 of a setscrew driver 104, as shown in FIG. 5B, for advancing the set screw 45along the passageway devices 31 and into the cages 42. The set screw 45may include threads 106 along its outer surface for rotatably engagingthe reduction threads 70 of the passageway devices 31 and the threads 68of the cages 42.

As shown in FIG. 6, the set screw driver 104 having a set screw 45connected to its distal end is inserted distally through incision 50 andalong the passageway device 31 extending through that incision 50. Acounter torque tube 108 can be used in conjunction with the insertionand advancement of the set screw 45 with the set screw driver 104, asalso shown in FIG. 6.

A perspective view of the counter torque tube 108 is shown in FIG. 7A.The counter torque tube 108 includes a tubular body 110 having aproximal end 112 and a distal end 114. A handle 116 is connected to thebody 110 at the proximal end 112 by a connection member 118. Theconnection member 118 may be a substantially tubular structureprojecting laterally from the proximal end 112 of the body 110, thetubular structure being configured to receive a stem 120 of the handle116 therein. The stem 120 may be secured within the connection member118 by one or more set screws (not shown) within one or more holes 122in the connection member 118. When connected to the connection member118, the handle 116 extends transverse to the longitudinal axis 119 ofthe body 110 and may extend substantially perpendicular to thelongitudinal axis 119.

The tubular body 110 of the counter torque tube 108 has an open interior124 designed to receive a passageway device 31 therein. A cross sectionof the counter torque tube 108 normal to the longitudinal axis 119 ofthe body 110 and taken along the axis of the handle 116 is shown in FIG.7B. As shown in the figure, the interior surface 126 defining the openinterior 124 includes opposing recessed grooves 128 or channels thereinextending along the length of the body 110. The grooves 128 arestructured to receive the blades 56 of the passageway device 31 when thecounter torque tube 108 receives the passageway device 31 therein. Asshown in FIG. 7B, the grooves 128 may have an arcuate shape along theplane normal to the longitudinal axis 119 of the body 110, which shapesubstantially matches the shape of the blades 56 in that plane. Thegrooves 128 include end surfaces 130 that constrain the blades 56 toremain in the grooves 128. As shown in FIG. 7B, the handle 116preferably extends from the body 110 along an axis 132, which isperpendicular to an axis 134. When the counter torque tube 108 isadvanced over one of the passageway devices 31 illustrated in FIGS. 1and 6, and the blades 56 are received within the grooves 128, the axis132 and the handle 116 desirably extends along the medial/lateral axis20, and the axis 134 desirably extends along the cephalad and caudaldirections 12, 14.

FIGS. 8A and 8B illustrate elevational views of a distal portion of thebody 110 of the counter torque tube 108, taken along orthogonaldirections. In particular, FIG. 8A is a view along axis 132, and FIG. 8Bis a view along axis 134. As shown in the figures, the counter torquetube 108 may include a distal edge 136 arranged to abut the proximal end54 of the cage 42 of the connecting element 30 when the body 110 of thecounter torque tube 108 is fully advanced along the passageway device31. In that regard, the cage 42 may be at least slightly wider than thepassageway device 31 such that further distal movement of the countertorque tube 108 is prevented when the distal edge 136 of the body 110comes into contact with the proximal end 54 of the cage 42. The distaledge 136 may be chamfered in order to ease bodily tissue aside duringinsertion of the counter torque tube 108. The counter torque tube 108may also include opposing extensions 138 extending distally beyond thedistal edge 136. At the distal ends of each of the extensions 138 is anarcuate cut-out 140 shaped to abut the rod 44. The length of eachextension 138 may be dimensioned such that, when the counter torque tube108 is fully advanced against the cage 42 of a connecting element 30,the contact between the cut-outs 140 and the rod 44 force the rod 44 tobe fully seated within the cage 42. When the counter torque tube 108 isfully advanced, each of the extensions 138 is preferably positionedalong a respective opening 139 (see FIG. 2A) defined between the arms 58of the cage 42. Moreover, the width of each extension 138 may bedimensioned such that the opposite edges 141 of each extension 138engage the respective edges 143 of the arms 58 along each opening 139.In that way, the engagement between the edges 141 of the extensions 138and the edges 143 of the arms 58 of the cage 42 desirably constrains therotational orientation of the cage 42 with respect to the body 110 ofthe counter torque tube 108 about the longitudinal axis 119.Alternatively, or in addition, the engagement between the blades 56 ofthe passageway device 31 and the grooves 128 of the counter torque tubebody 110 desirably provides a similar constraint in the rotationalorientation of the blade-screw 60 with respect to the body 110 of thecounter torque tube 108.

One or more windows 142 may be positioned on the counter torque tubebody 110 in alignment with the grooves 128 in the interior surface 126of the body 110. The windows 142 are positioned such that the proximaledges 144 of the blades 56 (see FIGS. 2A-B) are visible through one ormore of the windows 142 when the counter torque tube 108 is fullyadvanced against the connecting element 30. One or more laser markings,such as a line 146 bisecting the windows 142, may also be located on thecounter torque tube body 110, such that the lines 146 are aligned withthe proximal edges 144 of the blades 56 when the counter torque tube 108is fully advanced against the connecting element 30. Multiple windows142 (with or without corresponding lines 146) may be spaced apart alongthe longitudinal axis 119 of the body, and, as shown in FIG. 8B, one ormore of those windows 142 may have an opposing window 142 located acrossthe longitudinal axis 119 of the body. The locations of the variouswindows 142 and lines 146 along the longitudinal axis 119 of the body110 desirably correspond to the different lengths of blades 56 providedwith systems in accordance with some embodiments of the invention. Asdiscussed above, different length blades 56, or blade-screws 60 havingblades 56 of different lengths, may be provided with such systems toaccommodate different distances to be traversed for different sizedpatients. Reference markings 148 may be positioned near each window 142and/or line 146 to indicate which blade 56 length is associated withthat window 142 and/or line 146.

The counter torque tube 108 may also include one or more holes 150 alongat least a portion of the length of the body 110, preferably inalignment with the grooves 128 in the interior surface 126. Such holes150 may be sized and positioned such that any fluid (bodily orotherwise) and/or tissue that may have become trapped between the blades56 and the body 110 of the counter torque tube 108 (e.g., duringinsertion of the counter torque tube 108) may be released through theholes 150.

Returning to FIG. 6, the counter torque tube 108 may be advanced overone of the passageway devices 31, as shown in that figure. The countertorque tube 108 may be used in different ways. For example, whenadvancing the set screw 45 into engagement with the threads 70 of theblades 56 using the set screw driver 104, positioning the body 110 ofthe counter torque tube 108 around the passageway device 31 may help toalign the set screw driver 104 along the longitudinal axis 57 of theblade-screw 60, and thus help prevent cross-threading of the set screw45. In some embodiments, the coupling 72 may need to be removed from theblades 56 in order to allow the counter torque tube 108 to advance alongthe passageway device 31. In such cases, without the stability providedto the blades 56 by the coupling 72, the blades 56 may tend to pivot orflex slightly inwardly towards one another under pressure from thesurrounding tissue. The grooves 128 in the counter torque tube body 110,along with their end surfaces 130, however, preferably constrain thedesired positions of the blades 56 and provide stability to the blades56 when the counter torque tube 108 is advanced along the passagewaydevice 31. That stability provided by the counter torque tube 108desirably protects portions of the blade-screw 60, such as the frangibleportions 62 and the connections 69 between the blade extensions 63 andthe reduction portions 61, by preventing the blades 56 from becomingprematurely disconnected from the connecting element 30 and bypreventing the blade extensions 63 from becoming separated from thereduction portions 61. If the blades 56 pivot or flex slightly inwardlyupon removing the coupling 72, the set screw driver 104 may be advancedtogether with the counter torque tube 108 such that the set screw driver108 is positioned within the open interior 124 of the counter torquetube body 110 and such that the distal end of the set screw driver 104(with or without the set screw 45 connected to it) projects distallyfrom the distal end 114 of the body 110. Beneficially, in thisarrangement, the set screw driver 104 (and the set screw 45, ifconnected to it) will first pass between the proximal edges 144 of theblades 56 and will help to keep the proximal edges 144 apart when theyare engaged by the distal end 114 of the counter torque tube body 110and guided into the grooves 128. If the proximal edges 144 of the blades56 are not kept apart, the blades 56 might not properly be guided intothe grooves 128.

If, after being inserted in the body, the rod 44 is not fully seated inone or more of the cages 42 (e.g., the rod 44 is slightly proud), therod 44 can be further directed into a particular cage 42 in variousways. For example, the set screw 45 and set screw driver 104 can be usedto advance the rod 44 towards the cage 42. In one example, the set screwdriver 104 having a set screw 45 connected to its distal end can beadvanced within the passageway device 31 until the set screw 45 engagesthe rod 44 and pushes it distally. If the rod 44 is located proximallyof the reduction threads 70, the set screw driver 104 can be used topush the rod 44 distally until the set screw 45 contacts the reductionthreads 70. The rod 44 can then be further advanced towards the cage 42by rotating the set screw driver 104 to advance the set screw 45 alongthe reduction threads 70, which will further push the rod 44 towards thecage 42. Continued rotation of the set screw 45 will cause the set screw45 to engage and advance along the threads 68 of the cage 42 until therod 44 is fully seated within the cage.

In another example, the counter torque tube 108 can be used to push therod 44 towards the cage 42 by advancing the body 110 of the countertorque tube 108 distally along a passageway device 31 until the cut-outs140 at the distal end 114 of the body 110 engage the rod 44 and push itdistally. The counter torque tube 108 can be used in this manner toadvance the rod 44 for all or part of the distance to the cage 42. Forexample, the counter torque tube 108 can be used to advance the rod 44until the rod is within the region of the passageway device 31 havingthe reduction threads 70, after which the set screw 45 and set screwdriver 104 can be used to reduce the rod 44 the remaining distance intothe cage 42, as discussed above.

During the advancement of the set screw 45 along the reduction threads70 and/or the threads 68 of the cage 42, the body 110 of the countertorque tube 108 is desirably received around at least a portion of thepassageway device 31. Preferably, the distal end 114 of the tube body110 is positioned close to the set screw 45, and, more preferably, thedistal end 114 is advanced distally along the passageway device 31 whilethe set screw 45 is advanced. By positioning the counter torque tubebody 110 around the passageway device 31, the body 110 preferablyconstrains the blades 56 of the passageway device 31 to prevent theblades 56 from splaying outwardly during the threaded advancement of theset screw 45. Moreover, by positioning the counter torque tube 110 bodynear or in contact with the cage 42, the body 110 preferably constrainsthe arms 58 of the cage 42 to prevent the arms 58 from splayingoutwardly during the threaded advancement of the set screw 45.

During final tightening of the set screw 45 against the rod 44 withinthe cage 42, the counter torque tube 108 is desirably fully advancedagainst the cage 42. The full and proper advancement of the countertorque tube 108 can be checked by confirming that a proximal edge 144 ofone of the blades 56 of the passageway device 31 is aligned with theappropriate window 142 of the counter torque tube body 110, and, in someembodiments, is aligned with the appropriate laser marking or line 146.With the counter torque tube 108 fully advanced against the cage 42, thecounter torque tube 108 desirably constrains the rotational orientationof the cage 42 and/or the blades 56 of the passageway device 31, asdiscussed above. Therefore, during final tightening of the set screw 45,the surgeon or other user preferably firmly holds the handle 116 of thecounter torque tube 108 and/or provides any necessary torque to thehandle 116 in the direction opposite to the direction of rotation of theset screw 45. This will desirably prevent the torque being applied tothe set screw 45 by the set screw driver 104 from being transmitted tothe associated vertebra of the spine 10 via the connecting element 30,or at least reduce the amount of torque that is transmitted to thespine.

The final tightening of the set screw 45 in the cage 42 may be performedby the set screw driver 104, or the final tightening may be performed bya torque wrench (not shown). The torque wrench may have a similarstructure to the set screw driver 104, except that it may be constructedsuch that the torque applied by the torque wrench to the set screw 45 islimited to a pre-selected amount (e.g., 8 Nm (newton-meters)). Once aset screw 45 is finally tightened in one of the cages 42, as describedabove, the other cages 42 may be secured to the rod 44 by set screws 45in the same manner. Preferably, after the rod 44 is secured within atleast one of the cages 42 by a set screw 45, the rod inserter 84 may bedisconnected from the rod 44 and removed from the body.

Before final tightening of the set screw 45 in the cage 42, the relativepositions of the vertebrae may be adjusted. For example, while the rod44 is positioned within the cages 42 but before the set screw 45 istightened to the point that the cages 42 are locked with respect to therod 44, two or more vertebrae may be moved in the cephalad and caudaldirections 12, 14 towards one another (i.e., compression) and/or awayfrom one another (i.e., distraction). One system and method forperforming such compression and distraction is disclosed in U.S. Pat.No. 8,157,809 (“the '809 Patent”), the entire disclosure of which ishereby incorporated by reference herein as if fully set forth herein.Another similar system is illustrated in FIGS. 9A-13B and is discussedherein.

FIGS. 9A-B illustrate a hinge shaft 202 and a ball shaft 204 of acompression and distraction system 200. As shown in those figures, thehinge shaft 202 and the ball shaft 204 have been inserted into thepatient's body over and along a respective one of the passageway devices31. Similar to the compression and distraction assembly disclosed in the'809 Patent, the proximal end 206 of the hinge shaft 202 includes afulcrum or hinge 208, and the proximal end 210 of the ball shaft 204includes a ball 212. The hinge 208 can receive the ball 212 therein, asillustrated in FIG. 9B, and the hinge 208 can be rotated about theproximal end 206 of the hinge shaft 202 from the position illustrated inFIG. 9A to the position illustrated in FIG. 9B in order to receive theball 212. Once the ball 212 is received within the hinge 208 in themanner shown in FIG. 9B, a polyaxial fulcrum 214 is formed between theproximal ends 206, 210 of the shafts 202, 204 similar to that disclosedin the '809 Patent. Like the polyaxial fulcrum of the '809 Patent, thepolyaxial fulcrum 214 desirably allows all rotational degrees of freedomsuch that the fulcrum 214 does not impart ancillary stresses or motionto the vertebrae during compression or distraction.

FIGS. 10A-B illustrate elevational views of the hinge shaft 202, takenalong orthogonal directions. The hinge shaft 202 has a proximal end 206and a distal end 216, with the hinge 208 being at the proximal end 206.The hinge shaft 202 includes a proximal shaft 218 and a distal shaft220, with an eyelet ring 222 disposed therebetween. The distal shaft 220may have a similar structure to the body 110 of the counter torque tube108. That is, the distal shaft 220 desirably has a tubular shape with anopen interior designed to receive a passageway device 31 therein. Theopen interior may have the same grooved structure as the counter torquetube 108, in order to similarly receive and constrain the blades 56 ofthe passageway device 31. The distal end 216 may also have the samestructure for engaging the cage 42 of a connecting element 30 as thedistal end 114 of the counter torque tube body 110. That is, the distalend 216 may have a chamfered distal edge 224 arranged to abut theproximal end 54 of the cage 42 of the connecting element 30 when thehinge shaft 202 is fully advanced against the cage 42. The distal end216 may also include opposing extensions 226 with a cut out 228 shapedto abut the rod 44 and/or edges 230 for engaging the respective edges143 of the arms 58 of the cage 42. Also, the distal shaft 220 mayinclude one or more windows 232 and one or more laser markings, such aslines 234, arranged in the same manner as that described above withrespect to the counter torque tube 108, such that the full and properadvancement of the hinge shaft 202 can be determined based on alignmentwith the proximal edges 144 of the blades 56. The distal shaft 220 mayalso include one or more holes 236 along at least a portion of thelength of the distal shaft 220, preferably in alignment with the groovesin its interior surface. Such holes 236 are desirably sized andpositioned in the same manner as the holes 150 in the counter torquetube 108, in order to similarly release any trapped fluid and/or tissue.

The proximal shaft 218 of the hinge shaft 202 may be narrower along atleast a portion of its length, in order to reduce weight and material,and thus proximal shaft 218 may include a tapered portion 238. The hinge208 is a generally U-shaped component sized to fit the proximal end 206of the hinge shaft 202 between its ends 240. Each end 204 of the hinge208 is connected to the proximal end 206 by a respective pin 242 suchthat the hinge 208 may rotate from one side to the other (as shown inFIGS. 9A-B) about the pins 242. The proximal shaft 218 preferablyincludes a passageway along its length that is open at each end of theproximal shaft 218 and that communicates with the open interior of thedistal shaft 220. In that way, a tool, such as the set screw driver 104,can be passed down within the hinge shaft 202 through the open proximalend 206 in order to lock the position of the connecting element 30 withrespect to the rod 44 by tightening the set screw 45.

An eyelet ring 222 is located between the proximal shaft 218 and thedistal shaft 220. The eyelet ring 222 includes a laterally extending tab244 having a bore 246 formed within it. The bore 246 is configured toreceive a portion of one or more compression or distraction tools, asdiscussed below. Although the bore 246 may have an hourglass shape alongits central axis, as disclosed in the '809 Patent, the bore 246 mayalternatively have another shape, such as a substantially cylindricalshape along its central axis. The eyelet ring 222 is rotatable about thelongitudinal axis of the hinge shaft 202, such that the angular positionof the tab 244 around the hinge shaft 202 can be varied. The hinge shaft202 may be structured such that the eyelet ring 222 (and its tab 244) ispositioned in approximately the middle of the hinge shaft 202 along itslongitudinal axis, but the eyelet ring 222 could be positioned at otherlocations along the length of the hinge shaft 202.

The distal end 248 of the proximal shaft 218 may include a distalextension (not shown) which is received in the proximal end 250 of thedistal shaft 220. For example, the distal extension may be in the formof a sleeve which extends through the eyelet ring 222 and is press fitwithin the open interior of the proximal end 250 of the distal shaft220. The hinge shaft 202 may thus be assembled by advancing the distalextension of the proximal shaft 218 through the eyelet ring 222 and intothe open proximal end of the distal shaft 220. The proximal shaft 218 ispreferably not advanced too far into the distal shaft 220, so that theeyelet ring 222 received therebetween will not be compressed and havedifficulty rotating freely about the longitudinal axis of the hingeshaft 202. Once the proximal shaft 218 is properly received by thedistal shaft 220, the position of the shafts 218, 220 may be secured byinserting one or more pins 252 through respective aligned bores passingthrough the overlapping walls of the proximal and distal shafts 218,220. In one example, four such pins 252 are used for each hinge shaft202, spaced at 90° intervals about the longitudinal axis. After the pins252 are inserted, they are welded and blended within the bores until theouter surface of the hinge shaft 202 extending over the pins 252 issmooth.

FIGS. 11A-B illustrate elevational views of the ball shaft 204, takenalong orthogonal directions. The ball shaft 204 has a proximal end 210and a distal end 254, with the ball 212 being at the proximal end 210.The ball shaft 204 includes a proximal shaft 256 and a distal shaft 258,with an eyelet ring 260 disposed therebetween. The ball shaft 204includes numerous structures which are similar or identical tocorresponding structures of the hinge shaft 202. For example, the distalshaft 258 and the eyelet ring 260 of the ball shaft 204 may be identicalto the respective distal shaft 220 and eyelet ring 222 of the hingeshaft 202.

As with the distal shaft 220 of the hinge shaft 202, the distal shaft258 of the ball shaft 204 may have a similar structure to the body 110of the counter torque tube 108. That is, the distal shaft 258 desirablyhas a tubular shape with an open interior designed to receive apassageway device 31 therein. The open interior may have the samegrooved structure as the counter torque tube 108, in order to similarlyreceive and constrain the blades 56 of the passageway device 31. Thedistal end 254 may also have the same structure for engaging the cage 42of a connecting element 30 as the distal end 114 of the counter torquetube body 110 or the distal end 216 of the hinge shaft 202. That is, thedistal end 254 may have a chamfered distal edge 262 arranged to abut theproximal end 54 of the cage 42 of the connecting element 30 when theball shaft 204 is fully advanced against the cage 42. The distal end 254may also include opposing extensions 264 with a cut out 266 shaped toabut the rod 44 and/or edges 268 for engaging the respective edges 143of the arms 58 of the cage 42. Also, the distal shaft 258 may includeone or more windows 270 and one or more laser markings, such as lines272, arranged in the same manner as described above with respect to thecounter torque tube 108 or the hinge shaft 202, such that the full andproper advancement of the ball shaft 204 can be determined based onalignment with the proximal edges 144 of the blades 56. The distal shaft258 may also include one or more holes 274 along at least a portion ofthe length of the distal shaft 258, preferably in alignment with thegrooves in its interior surface. Such holes 274 are desirably sized andpositioned in the same manner as the holes 150 in the counter torquetube 108 or the holes 236 in the hinge shaft 202, in order to similarlyrelease any trapped fluid and/or tissue.

The proximal shaft 256 of the ball shaft 204 may be narrower along atleast a portion of its length, in order to reduce weight and material,and thus proximal shaft 256 may include a tapered portion 276. The ball212 is a generally spherical component sized to fit within the hinge 208to form the polyaxial fulcrum 214. The proximal shaft 256 preferablyincludes a passageway along its length that is open at each end of theproximal shaft 218 and that communicates with the open interior of thedistal shaft 258. In that way, a tool, such as the set screw driver 104,can be passed down within the ball shaft 204 through the open proximalend 210 in order to lock the position of the connecting element 30 withrespect to the rod 44 by tightening the set screw 45.

An eyelet ring 260 is located between the proximal shaft 256 and thedistal shaft 258. The eyelet ring 260 includes a laterally extending tab278 having a bore 280 formed within it. The bore 280 is configured toreceive a portion of one or more compression or distraction tools, asdiscussed below. Although the bore 280 may have an hourglass shape alongits central axis, as disclosed in the '809 Patent, the bore 280 mayalternatively have another shape, such as a substantially cylindricalshape along its central axis. The eyelet ring 260 is rotatable about thelongitudinal axis of the ball shaft 204, such that the angular positionof the tab 278 around the ball shaft 204 can be varied. The ball shaft204 may be structured such that the eyelet ring 260 (and its tab 278) ispositioned in approximately the middle of the ball shaft 204 along itslongitudinal axis, but the eyelet ring 260 could be positioned at otherlocations along the length of the ball shaft 204.

The ball shaft 204 may be assembled in the same manner as the hingeshaft 202. In particular, the proximal shaft 256 may be press fit orotherwise received within the distal shaft 258, and then the position ofthe shafts 256, 258 may be secured by inserting one or more pins 282through respective aligned bores passing through the overlapping wallsof the proximal and distal shafts 256, 258. Four such pins 282 may beinserted into the ball shaft 204, spaced at 90° intervals about thelongitudinal axis, after which the pins 282 may be welded and blendedwithin the bores until the outer surface of the ball shaft 204 extendingover the pins 282 is smooth.

FIG. 12A illustrates an embodiment of a distractor 284 for use inconjunction with the present invention. The distractor 284 may beidentical in structure and function to the distraction pliers disclosedin the '809 Patent. For example, the distractor 284 may include a firsthandle 286 and a second handle 288 pivotably connected together at apivot point 287. Each of the first and second handles 286, 288 has a tipend 290 and a ratchet end 292. A tip 294, which may have a generallycylindrical shape, is formed at the tip end 290 of each handle 286, 288,and a ratchet 296 for locking the distraction position of the distractor284 extends between the handles 286, 288 at the ratchet end 292.

FIG. 13A illustrates an embodiment of a compressor 298 for use inconjunction with the present invention. The compressor 298 may beidentical in structure and function to the compression pliers disclosedin the '809 Patent. For example, the compressor 298 may include a firsthandle 300 and a second handle 302 pivotably connected together at apivot point 301. Each of the first and second handles 300, 302 has a tipend 304 and a ratchet end 306. A tip 308, which may have a generallycylindrical shape, is formed at the tip end 304 of each handle 300, 302,and a ratchet 310 for locking the compression position of the compressor298 extends between the handles 300, 302 at the ratchet end 306.

One method of using the compression and distraction system 200 is byinserting the hinge shaft 202 and the ball shaft 204 over and alongrespective passageway devices associated with connecting elements 30attached to the vertebrae 24, 26 that the surgeon or other user desiresto move relative to one another. It is noted that the hinge shaft 202and ball shaft 204 can be inserted without regard to the orientation ofthe tabs 244, 278 of the respective eyelet rings 222, 260. Indeed,because the eyelet rings 222, 260 are rotatable about the longitudinalaxes of the respective hinge shaft 202 and ball shaft 204, the tabs 244,278 can be properly oriented after the hinge shaft 202 and ball shaft204 are inserted. In order to align the tabs 244, 278, the ring 222 ofthe hinge shaft 202 is rotated until the tab 244 is directed away fromthe ball shaft 204 along the cephalad or caudal direction 12, 14, andthe ring 260 of the ball shaft 204 is rotated until the tab 278 isdirected away from the hinge shaft 202 along the cephalad or caudaldirection 12, 14, as shown in FIGS. 9A-B. Similarly, the hinge shaft 202and ball shaft 204 can desirably be inserted without regard to theorientation of the hinge 208 of the hinge shaft 202. That is, the hinge208 is preferably symmetrical, such that it can engage the ball 212 ofthe ball shaft 204 (whether the ball shaft 202 is displaced in thecephalad direction 12 or the caudal direction 14 from the hinge shaft202) by rotating the hinge 208 about the proximal end 206 of the hingeshaft 202 and towards the ball shaft 204 in either the cephaladdirection 12 or the caudal direction 14. Thus, after the hinge shaft 202and ball shaft 204 are inserted, the hinge 208 is rotated about theproximal end 206 of the hinge shaft 202 until the ball 212 of the ballshaft 204 is received within the hinge 208 as shown in FIG. 9B. Next,the hinge shaft 202 and ball shaft 204, and the associated vertebrae 24,26, are distracted apart using the distractor 284 or compressed towardsone another using the compressor 298, as shown in FIGS. 12B and 13B,respectively, and discussed below.

FIG. 12B illustrates the distractor 284 engaging the hinge shaft 202 andthe ball shaft 204 to distract apart the vertebrae 24, 26 connectedthereto. In particular, the tips 294 of the distractor 284 are insertedinto respective bores 246, 280 of the hinge shaft 202 and ball shaft204, respectively. Then, the handles 286, 288 are pressed together,which causes the tips 294 to move away from each other. The hinge shaft202 and ball shaft 204 are thus caused to pivot about the polyaxialfulcrum 214 such that the distal ends 216, 254 of the respective hingeshaft 202 and ball shaft 204 separate the respective connecting elements30 and distract the associated vertebrae 24, 26. Once the first andsecond handles 286, 288 are pressed to impart an appropriate amount ofdistraction to the vertebrae, they are locked in that position by theratchet 296. The vertebrae 24, 26 may then be held in that position bythe distractor 284 until the surgeon or other user fixes the relativepositions of the vertebrae 24, 26. That fixation may be performed byinserting a tool, such as the set screw driver 104, through each of thehinge shaft 202 and ball shaft 204, and then tightening a set screw 45against the rod 44 in each of the connecting elements 30 connected tothe vertebrae 24, 26 to be fixed.

FIG. 13B illustrates the compressor 298 engaging the hinge shaft 202 andthe ball shaft 204 to compress together the vertebrae 24, 26 connectedthereto. In particular, the tips 308 of the compressor 298 are insertedinto respective bores 246, 280 of the hinge shaft 202 and ball shaft204, respectively. Then, the handles 300, 302 are pressed together,which causes the tips 308 to move towards each other. The hinge shaft202 and ball shaft 204 are thus caused to pivot about the polyaxialfulcrum 214 such that the distal ends 216, 254 of the respective hingeshaft 202 and ball shaft 204 move the respective connecting elements 30closer together and compress the associated vertebrae 24, 26. Once thefirst and second handles 300, 302 are pressed to impart an appropriateamount of compression to the vertebrae, they are locked in that positionby the ratchet 310. The vertebrae 24, 26 may then be held in thatposition by the compressor 298 until the surgeon or other user fixes therelative positions of the vertebrae 24, 26. That fixation may beperformed by inserting a tool, such as the set screw driver 104, througheach of the hinge shaft 202 and ball shaft 204, and then tightening aset screw 45 against the rod 44 in each of the connecting elements 30connected to the vertebrae 24, 26 to be fixed.

If performing final tightening of a set screw 45 into a connectingelement 30 to which a hinge shaft 202 or a ball shaft 204 are connected,the counter torque tube 108 can be advanced against the cage 42 of anadjacent vertebra to help reduce the amount of torque that istransmitted to the spine 10.

During compression or distraction, the eyelet rings 222, 260 may rotateabout the respective longitudinal axes of the hinge shaft 202 and ballshaft 204 while engaged with the tips 294, 308 of the respectivecompressor 298 or distractor 284. That is, if the bores 246, 280 of therespective eyelet rings 222, 260 have a substantially cylindrical ratherthan an hourglass shape along their central axes, as discussed above,such rotation may permit the tips 294, 308 to follow an arcuate pathabout the pivot points 287, 301 of the respective compressor 298 ordistractor 284. Also, during the compression or distraction, theconnecting elements 30 connected to the hinge shaft 202 and ball shaft204 may move with respect to the rod 44 as the connecting elements 30are displaced relative to one another. In one alternative, one of theset screws 45 (either the one associated with the connecting element 30connected to the hinge shaft 202 or the one associated with theconnecting element connected to the ball shaft 204) may be tightenedagainst the rod 44 before compression or distraction is performed. Inthat way, a one-way displacement may be induced, where the non-tightenedconnecting element 30 is moved along the rod 44 during compression ordistraction.

After completing compression or distraction between two adjacentvertebrae 24, 26, the compression and distraction system 200 may be usedto perform compression or distraction between two other vertebrae (e.g.,one vertebra 24 previously engaged for compression/distraction and thenext adjacent vertebra 22). In that case, the entire compression anddistraction system 200 need not be removed from the body. Rather, one ofthe hinge shaft 202 or ball shaft 204 may be moved to that next adjacentvertebra 22, and the tabs 244, 278 may be rotated accordingly, and thehinge 208 may be flipped to engage the ball 212 of the ball shaft 204.For example, with reference to FIGS. 9A-B, after compression ordistraction is completed between vertebrae 24 and 26, the ball shaft 24may be repositioned over and along the passageway device 31 connected tovertebra 22. Then the ring 222 of the hinge shaft 202 is rotated untilthe tab 244 is directed away from the ball shaft 204 along the cephalador caudal direction 12, 14, and the ring 260 of the ball shaft 204 isrotated until the tab 278 is directed away from the hinge shaft 202along the cephalad or caudal direction 12, 14. The hinge 208 can then berotated about the proximal end 206 of the hinge shaft 202 in the caudaldirection 14 and into engagement with the ball 212 of the ball shaft204. Compression or distraction can then be performed between thevertebrae 22, 24 as described above.

After the various set screws 45 are finally tightened into the cages 42,the passageway devices 31 can be detached from the respective connectingelements 30 and removed from the body. For example, the blades 56 of thepassageway devices 31 may be separately disconnected from the connectingelements 30 and removed from the body. If monolithic blade-screws 60were used, the blades 56 may be disconnected from the connecting element30 by breaking each of the blades 56 away from the connecting element 30at the frangible portions 62.

One method for breaking the blades 56 of the blade-screw 60 away fromthe connecting element 30 is by using a blade remover 312, illustratedin FIG. 14A. The blade remover 312 is an elongate tool having a proximalend 314 and a distal end 316. The blade remover 312 may include a handle318 at the proximal end 314 and may have a channel (not shown) formedtherein open to the distal end 316. The channel may be constructed toreceive a blade 56 of a blade-screw 60 therein. The blade remover 312may also include a window and a laser marking (not shown) (or multiplewindows and laser markings, if multiple blades 56 with different lengthsare used), as described above with respect to the counter torque tube108, the hinge shaft 202, and the ball shaft 204, in order to determinewhether the blade remover 312 has been fully and properly advanced alongthe blade 56. The blade remover 312 may include a spring clip 322 incommunication with the channel such that the spring clip 222 securelyengages a blade 56 when the blade 56 is positioned within the channel,preferably in order to retain the blade 56 within the blade remover 312after the blade 56 has been detached from the connecting element 30. Theblade remover 312 may also include a release mechanism for ejecting theblade 56 from the channel after the detached blade 56 has been removedfrom the body. That release mechanism may include a slider 324 receivedwithin a longitudinal track, such as a slot 326, extending along theblade remover 312. The release mechanism is structured such that distalmovement of the slider 324 along the track will push the blade 56 out ofthe channel at the distal end 316 of the blade remover 312.

In use, the blade remover 312 is engaged to a blade 56 by sliding theblade remover 312 distally over the blade 56 until the blade is receivedwithin the channel, as illustrated in FIG. 14B. Using the handle 318, asurgeon or other user may pivot the blade remover 312, and thus theblade 56 received therein, about the frangible portion 62 until thefrangible portion 62 fractures, thus disconnecting the blade 56 from theconnecting element 30. As illustrated in FIG. 14C, each blade 56 may bepivoted away from the adjacent blade 56 of the same blade-screw 60. Theblade remover 312 may then be removed from the body, and desirably thespring clip 322 may retain the blade 56 within the blade remover 312until the blade remover 312 is removed from the body. After the bladeremover 312 is removed from the body, the detached blade 56 may beejected from the channel by actuating the release mechanism. As shown inFIG. 14D, the slider 324 is moved distally along the blade remover 312until the blade 56 is ejected from the distal end 316 of the bladeremover 312. The blade remover 312 may then be used again by repeatingthe above steps to remove other blades 56 from the connecting elements30.

If one or both blades 56 of one of the passageway devices 31 were tobecome prematurely disconnected from a connecting element 30, andfurther access to the connecting element 30 is desired, one or more ofthe blade rescue retractors of the blade rescue system disclosed in the'098 Application may be used as functional replacements for the missingblade(s), as disclosed in that application. In order to ease theinsertion of such a blade rescue retractor into the body, a series ofsequential dilators may be inserted to gently enlarge a path to thetargeted connecting element 30, with the largest of the dilators beingsized to receive one of the blade rescue retractors inside of it.Thereafter, all but the largest of the sequential dilators may beremoved, and then the blade rescue retractor may be advanced within thelargest dilator to the connecting element 30. After the blade rescueretractor reaches the connecting element 30, the largest dilator may beremoved from the body.

Although various components described herein, such as the counter torquetube 108, the hinge shaft 202, and the ball shaft 204, have beendescribed and illustrated as being designed to interact with the blades56 of passageway devices 31, it is to be understood that thosecomponents could be designed to interact with different types ofpassageway devices, such as cannulas, towers, or portals, some of whichmay not have blades 56. In such cases, those components may be designedto interact similarly with those other types of passageway devices. Forexample, the open interiors of the counter torque tube 108, hinge shaft202, and ball shaft 204 may be structured to receive such other type ofpassageway device, and the interior surfaces of those components mayhave recessed grooves that have a correspondingly different shape, orthe interior surfaces may have other structures for receiving orotherwise engaging corresponding structures of the passageway device.Moreover, the windows and the laser markings (e.g., lines) may bedesigned to align with a predetermined portion of the passageway device,such as the proximal end of the passageway device.

The various components described herein are preferably constructed ofmaterials safe for use in the body. In one embodiment, many of thecomponents to be permanently implanted in the body, such as theblade-screws 60 and the rod 44, may be constructed from titanium or atitanium alloy. In one alternative, some or all of such permanentlyimplantable components may be constructed from a cobalt-chromium alloy,such as the material sold under the trademark VITALLIUM® by HowmedicaOsteonics Corp. Many or all of the instruments for use in implanting andmanipulating the permanently implantable components, such as the rodinserter 84, the counter torque tube 108, the blade remover 312, and thecomponents of the compression and distraction system 200 (including thehinge shaft 202, the ball shaft 204, the distractor 284, and thecompressor 298), may be entirely, largely, or partially constructed fromstainless steel.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. A method of constructing a monolithicblade-screw, comprising: providing a connecting element including ascrew coupled to a cage, the cage adapted to receive a spinal fusion rodtherein, and having a reduction portion connected thereto at a frangibleportion, the reduction portion having a first set of threads adapted toengage a set screw; permanently affixing a distal end of a bladeextension to a proximal end of the reduction portion.
 2. The method ofclaim 1, further comprising integrally forming the cage and thereduction portion from a single piece of material.
 3. The method ofclaim 2, wherein the step of permanently affixing the distal end of theblade extension to the proximal end of the reduction portion includeswelding the distal end of the blade extension to the proximal end of thereduction portion.
 4. The method of claim 2, wherein the cage includes asecond set of threads therealong in alignment with the first set ofthreads of the reduction portion, and wherein the blade extension is notthreaded.
 5. The method of claim 4, wherein the threads of the first andsecond sets of threads have a generally horizontal flank facing towardsthe screw.
 6. The method of claim 1, further comprising modifying theshape of a component forming the blade extension.
 7. The method of claim6, wherein the modifying step occurs before the affixing step.
 8. Themethod of claim 6, wherein the modifying step occurs after the affixingstep.
 9. The method of claim 6, wherein the modifying step is performedby wire-cut electrical discharge machining.
 10. The method of claim 1,wherein the screw is polyaxially coupled to the cage.
 11. The method ofclaim 1, further comprising coupling the screw to the cage before thestep of providing the connecting element.